MFC r325834,r325997,326502: Move sys/boot to stand/

This is effectively a direct commit to stable/11, due to differences between
stable/11 and head. Changes to DTS in sys/boot/fdt/dts were often
accompanied by kernel changes. Many of these were also risc-v updates that
likely had many more dependencies to MFC.

Because of this, sys/boot/fdt/dts remains as-is while everything else in
sys/boot relocates to stand/.

r325834: Move sys/boot to stand. Fix all references to new location

r325997: Remove empty directories.

r326502: Document the sys/boot -> stand move in hier.7 and the top-level README.

MFC r307322,r307323,r307324,r307326,r307327,r307338,r307879,r307908,r307911,
r307942,r307950,r307951,r307954,r307955,r308125,r308195,r308476,r308534,
r308535,r308776,r308843,r310236,r310726: Loader fixes, 2016q4

r307322: Remove /boot/boot.conf, deprecated for 16 years

r307323: Remove fetching of pInterp.

r307324: Create a new linker set, Xficl_compile_set which contains a list of
functions to call to register new forth words.

r307326: In UEFI mode expose the SMBIOS anchor base address via kenv

r307327: Update i386 build of loader.efi (but leave it disabled) so that we
at least build it now.

r307338: Create a pcibios-version environment FORTH word.

r307879: Preliminary support for EFI in boot loader.

r307908: Fix the build on both arm64 and when WITHOUT_FORTH is defined.

r307911: Add better comment...

r307942: Really make WITHOUT_FORTH (MK_FORTH==no) work.

r307950: Add it (Makefile.ficl) to the right place

r307951: Fix two backwards tests.

r307954: Back out the move to the loader script from -N.

r307955: LIBSTAND goes last, so put it last here too.

r308125: In loader.efi, instead of exiting directly, try to fallback.

r308195: efinet_dev_print should honor verbose option.

r308476: boot/forth spelling issue in forth word

r308534: The file_loadraw function grew an argument, update install function

r308535: Add support for LOADER_RC setting in the pkgfs manifes

r308776: loader: zfs toplevel vdev must have spa set.

r308843: loader: smbios version check is not correct

r310236: Renumber license clauses to avoid skipping #3

r310726: cdboot: add explict suffix to ambiguous or instruction

PR: 214375

MFC r306264: Use 32-bit value for .text padding, for linker portability

GNU ld interprets the padding value as a variable-length byte string,
while GNU gold and LLVM lld interpret it as a 32-bit value.

MFC r305854: Use arch-specific .text padding fill value in EFI loaders

The fill pattern was previously an ia64 instruction sequence. Presumably
ia64's linker script was copied as a starting point.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Move i386/efi files to new home in efi/loader/arch/i386

This was not (and still is not) connected to the build, but the EFI
loader is in the process of being built for other than amd64 so these
files ought to live in their eventual MD location.

EFI boot loader for FreeBSD/i386.

Doesn't boot a kernel yet, but it can read an ELF file from the EFI FAT
partition.